In this study we investigated genetic variation in three populations of elephant seals, two of the southern species (Mirounga leonina), one of the northern species (M. angustirostris), and two species of fur seal (Arctocephalus gazella and A. fostori). The two species in each genus are very closely related. The northern elephant seal and the Antarctic fur seal (A. gazella) were hunted extensively in the last century, and have since recovered to over 100,000 seals (the northern elephant seal) and over 1,000,000 seals (the Antarctic fur seal). Previously we investigated the extent of the northern elephant seal bottleneck using a simulation model approach, determined life history parameters using hypervariable DNA markers, and assessed the level of post-bottleneck variation in several molecular and quantitative genetic characters. Research in the current year focussed on extending applications of the model, and on the microsatellite and major histocompatibility complex data. The results permit a detailed analysis of the effects of inbreeding on genetic variation in a natural population, and provide insight into the ways in which variation accumulates and is maintained.